The primary mission of CORE A is to provide high quality nocturnal polysomnograms (NPSGs) and multiple sleep latency tests (MSLT) for a number of SCOR projects. This will include males and females of different age groups, spanning the whole spectrum of sleep disordered breathing. We, also envision the CORE A as and ideal site for development and validation of methods. The following objectives will be specifically addressed: 1) To quantify sleep disordered breathing in a large number of subjects using standard NPSGs and to document the degree of daytime sleepiness using the multiple sleep latency test (project 4 and 3). 2) To validate the standard NPSG determination of the type of apnea or hypopnea in a relatively large subset of subjects. This will be accomplished by the use of a pharyngeal catheter during routine NPSGs (project 3). 3) To develop and validate automated NPSG scoring methods (projects 4 and 3). 4) To quantify sleep state instability and to correlate it with respiratory instability (projects 2 and 3. 5) To provide unattended acquisition of respiratory variables outside the Sleep Laboratory (projects 4, 3 and 5).